Oscillation generation



March 7,-1939. N` E, UNDENBLAD l' 2,149,450

OSCILLATION GENERATION Original Filedan. 14, 1933 I-Ilw Q mh a u lAAAAAAA "I I "vvv" INVENTOR ATTORNEY Patented Mar. 7, 1939 UNITED STATESPATENT OFFRE or to Radio Corporation of ration of Delaware America, acorpo- Original application January 14, 1933, Serial No.

651,809, now

patent No. 2,052,888, dated Septomber 1, 1936. Divided and thisapplication May 23, 1936, Serial No. 81,359

2 Claims.

My U. S. application Ser. No. 700,252, led Nov.

29, 1933, Patent #2,054,431, dated September 15,

1936, relates to ultra-short wave signalling and in particular to anovel method of and circuit 5 for wobbling and/or modulating ultra-highfrequency oscillations to increase the effectiveness thereof and/or tosignal therewith. The invention disclosed in said application, which isequally applicable to longer waves and to phase modulam tion, as well asfrequency modulation,

tinuation in part of U. S. application Ser. No. 651,809, led Jan. 14,1933, Patent #2,052,888, dated September 1, 1936.

In each of the applications referred to above, I modulate the characterof a carrier wave in accordance with modulating potentials. Thesemodulating potentials may represent voice frequencies or tonefrequencies. The present application, which is a division of my U. S.applica- 2O tion Ser. No. 651,809, filed Jan. 14, 1933, Patent#2,052,888, dated September 1, 1936, discloses a novel means forproducing oscillations and increasing the frequency thereof. Theoscillations may be used for modulating the transmitters of theaforesaid applications when a keyed tone frequency is to be transmittedon the carrier wave. Of course, I do not limit my invention to such usesince obviously the generated oscillations may be put to Wide use in theradio art.

In describing my invention in detail. reference will be made to thedrawing wherein I have shown in Fig, 1 a generator and a harmonicproducer connected therewith arranged in accordance with the presentinvention. In Fig, 2, I have shown a curve illustrating the character ofa non-linear resistor or impedance used in the harmonic producingcircuits.

Referring to Fig. 1, screen grid tube 28 connected regeneratively, asshown, to function as w an audio frequency oscillator, is turned on andoff by the action of switch 30. The latter switch is in turn operated bymeans of a key 32 causing the electromagnet 34 to move contact 36 to itsupper position. Opening of key 32, of course, allows 36 to fall upon itslower contact. In its lower position, a large negative bias is impressedupon the grid of tube 38 as a result of which little current is drawnthrough resistor 40, allowing suflicient plate potential to be appliedto tube 28 to cause it to oscillate at an audio frequency rate dependingupon, in general, the tuning of grid circuit 42. In its upper position,contact 36 causes the grid of tube 38 to assume such a potential as toallow passage of current therethrough as a result of which there is sucha fall (Cl. Z50- 36) of potential across resistor 40 as to reduce theplate potential of tube 28 to an inoperative value. Consequently, in itsupper position, armature 38 will prevent the generation of audiofrequency currents and their subsequent passage through condenser 44. Ifdesired, this primary audio frequency so generated and so keyed on andolf, may be used for modulation purposes in the transmitters of my priorapplications or may put to any use known in the radio art.

However, if desired, the audio frequency generated by tube 28 may befrequency multiplied before use.

One way of doing this is to feed the audio frequency generated throughcondenser 44 to a distorting resistor 48, the biasing current throughwhich is supplied by source of potential 3! and controlled by Variableresistor 52. The resistor 48 has a characteristic such as illustrated inFig. 2 wherein a relatively small increase causes a disproportionateincrease of current through it. In this curve, the ordinates indicatethe current passed by the distorting resistance and the abscissaindicate applied potential. Consequently, application of audio frequencycurrent to the distorting resistor 48, will cause the wave form ofcurrent passing therethrough to become distorted as a result of which,in the serially tuned circuit 33, preferably tuned to a desiredharmonic, harmonic frequency energy may be derived which may be fed bymeans of conductor 31 to any utilization circuit. The resistor may be ofa material called Thyrite,

However, if desired, the harmonic frequency energy may be resonated in aparallel tuned circuit 39 and amplified by means of electron dischargedevice 4l. By a suitable choice of bias from source 3l for device 4|, asdisclosed in the copending application of C. W. Hansell, Serial No.177,505, filed March 23, 1927, Patent #1,878,- 308, dated September 20,1932, a further harmonic may be generated in the parallelly tuned outputcircuit 43 of tube 4|. However, it may be desired to use tube 4! merelyas an amplifier in which case the output cuit 43 may be fed into afurther distorting resistor 45 polarized by source 49 and maintained ata suitable operating point by adjustment of resistor 5i. A furtherharmonic will then be generated in parallelly tuned circuit 55 keyed ormodulated in accordance with the actuation of keying switch 32. Ifdesired, this harmonic may be fed through conductor 52 to anyutilization circuit, or, it may be amplied by means of tube in potentialenergy appearing in cir- "i Cil 54 and then fed through conductor 56 toany utilization circuit.

What is claimed is:

1. In means for multiplying the frequency of Wave energy, a source ofWave energy, an ohmic resistance of the type in which the current owVaries non-linearly With respect to the applied potential, meansconnecting one terminal of said resistance to a point on said source ofWave en'- ergy, a circuit series tuned to a harmonic of the frequency ofsaid Wave energy connecting the other terminal of said resistance to a.point on said source of Wave energy and a parallel tuned circuitresonant at a frequency which is a harmonic of the frequency of the waveenergy of said source connected in parallel with a portion of saidseries tuned circuit, and means for deriving harmonic energy from saidparallel tuned resonant circuit.

2. Wave energy producing means comprising in combination, a source ofoscillatory energy, a

resistive element of the type, the ow of current through Which changesat a rate diierent than the rate at which potential applied to saidelement for causing said flow of current is changed, a circuit seriestuned to a harmonic of the frequency of said oscillatory energyconnecting said resistive element in shunt to said source of oscillatoryenergy for impressing oscillatory energy from said source of oscillatoryenergy on said resistive element, an alternating current circuitparallel tuned to a frequency which is a harmonic of the frequency ofsaid oscillatory energy, means connecting said parallel tuned circuit inshunt to a portion of said series tuned circuit for impressing energyfrom said resistive element on said parallel tuned alternating currentcircuit, and means for deriving energy of a harmonic frequency from oneof said circuits. v

N'ILS E. LINDENBLAD.

